✨ feat(models-sync): official upstream sync with conflict resolution UI, opt‑out flag, and backend resiliency

Backend
- Add endpoints:
  - GET /api/models/sync_upstream/preview — diff preview (filters out models with sync_official = 0)
  - POST /api/models/sync_upstream — apply sync (create missing; optionally overwrite selected fields)
- Respect opt‑out: skip models with sync_official = 0 in both preview and apply
- Return detailed stats: created_models, created_vendors, updated_models, skipped_models, plus created_list / updated_list
- Add model.Model.SyncOfficial (default 1); auto‑migrated by GORM
- Make HTTP fetching robust:
  - Shared http.Client (connection reuse) with 3x exponential backoff retry
  - 10MB response cap; keep existing IPv4‑first for *.github.io
- Vendor handling:
  - New ensureVendorID helper (cache lookup → DB lookup → create), reduces round‑trips
  - Transactional overwrite to avoid partial updates
- Small cleanups and clearer helpers (containsField, coalesce, chooseStatus)

Frontend
- ModelsActions: add “Sync official” button with Popover (p‑2) explaining community contribution; loading = syncing || previewing; preview → conflict modal → apply flow
- New UpstreamConflictModal:
  - Per‑field columns (description/icon/tags/vendor/name_rule/status) with column‑level checkbox to select all
  - Cell with Checkbox + Tag (“Click to view differences”) and Popover (p‑2) showing Local vs Official values
  - Auto‑hide columns with no conflicts; responsive width; use native Semi Modal footer
  - Full i18n coverage
- useModelsData: add syncing/previewing states; new methods previewUpstreamDiff, applyUpstreamOverwrite, syncUpstream; refresh vendors/models after apply
- EditModelModal: add “Participate in official sync” switch; persisted as sync_official
- ModelsColumnDefs: add “Participate in official sync” column

i18n
- Add missing English keys for the new UI and messages; fix quoting issues

Refs
- Upstream metadata: https://github.com/basellm/llm-metadata

web/src/hooks/models/useModelsData.jsx

@@ -95,6 +95,8 @@ export const useModelsData = () => {
   const [showAddVendor, setShowAddVendor] = useState(false);
   const [showEditVendor, setShowEditVendor] = useState(false);
   const [editingVendor, setEditingVendor] = useState({ id: undefined });
+  const [syncing, setSyncing] = useState(false);
+  const [previewing, setPreviewing] = useState(false);
 
   const vendorMap = useMemo(() => {
     const map = {};
@@ -163,6 +165,81 @@ export const useModelsData = () => {
     await loadModels(page, pageSize);
   };
 
+  // Sync upstream models/vendors for missing models only
+  const syncUpstream = async () => {
+    setSyncing(true);
+    try {
+      const res = await API.post('/api/models/sync_upstream');
+      const { success, message, data } = res.data || {};
+      if (success) {
+        const createdModels = data?.created_models || 0;
+        const createdVendors = data?.created_vendors || 0;
+        const skipped = (data?.skipped_models || []).length || 0;
+        showSuccess(
+          t(
+            `已同步：新增 ${createdModels} 模型，新增 ${createdVendors} 供应商，跳过 ${skipped} 项`,
+          ),
+        );
+        await loadVendors();
+        await refresh();
+      } else {
+        showError(message || t('同步失败'));
+      }
+    } catch (e) {
+      showError(t('同步失败'));
+    }
+    setSyncing(false);
+  };
+
+  // Preview upstream differences
+  const previewUpstreamDiff = async () => {
+    setPreviewing(true);
+    try {
+      const res = await API.get('/api/models/sync_upstream/preview');
+      const { success, message, data } = res.data || {};
+      if (success) {
+        return data || { missing: [], conflicts: [] };
+      }
+      showError(message || t('预览失败'));
+      return { missing: [], conflicts: [] };
+    } catch (e) {
+      showError(t('预览失败'));
+      return { missing: [], conflicts: [] };
+    } finally {
+      setPreviewing(false);
+    }
+  };
+
+  // Apply selected overwrite
+  const applyUpstreamOverwrite = async (overwrite = []) => {
+    setSyncing(true);
+    try {
+      const res = await API.post('/api/models/sync_upstream', { overwrite });
+      const { success, message, data } = res.data || {};
+      if (success) {
+        const createdModels = data?.created_models || 0;
+        const updatedModels = data?.updated_models || 0;
+        const createdVendors = data?.created_vendors || 0;
+        const skipped = (data?.skipped_models || []).length || 0;
+        showSuccess(
+          t(
+            `完成：新增 ${createdModels} 模型，更新 ${updatedModels} 模型，新增 ${createdVendors} 供应商，跳过 ${skipped} 项`,
+          ),
+        );
+        await loadVendors();
+        await refresh();
+        return true;
+      }
+      showError(message || t('同步失败'));
+      return false;
+    } catch (e) {
+      showError(t('同步失败'));
+      return false;
+    } finally {
+      setSyncing(false);
+    }
+  };
+
   // Search models with keyword and vendor
   const searchModels = async () => {
     const { searchKeyword = '', searchVendor = '' } = getFormValues();
@@ -398,5 +475,12 @@ export const useModelsData = () => {
 
     // Translation
     t,
+
+    // Upstream sync
+    syncing,
+    previewing,
+    syncUpstream,
+    previewUpstreamDiff,
+    applyUpstreamOverwrite,
   };
 };